Added Ticktock of the Clock Restarts Time Debate

And unlike leap years or daylight saving time, software designers cannot plan ahead because leap seconds get added only when they are needed. The current seven-year hiatus is twice as long as any previous gap.

"At some point this will become so annoying that someone will want to change it," said astronomer Dennis McCarthy, retired director of the U.S. Naval Observatory's Directorate on Time and an advocate of abolishing the leap second. "I'm quite confident that people are not going to be happy with multiple leap seconds per year."

So why not get rid of them? Industry could enjoy the regularity of atomic clocks without risking technological collapse on New Year's Eve. And the divergence from solar time would not be more than one or two seconds per year, perhaps two minutes per century.

"The idea that it's going to be midnight in the middle of the afternoon is just nonsense," Levine said.

Others, however, suggest that the hardship caused by leap seconds may be overblown, if not illusory, as experts on both sides of the debate agree that there is little data beyond a few anecdotes to suggest that leap seconds have in the past created havoc in time-sensitive endeavors.

"The case hasn't been made," said University of Virginia astronomer Ken Seidelmann. "All there is is rumor that they're inconvenient, but we've had them for 30-plus years and there's no outcry. I see no reason to get rid of them."

Furthermore, Seidelmann added, astronomers and satellite operators deploy sensitive equipment on the ground and in space on the assumption that the Coordinated Universal Time signal will match up within a second of astronomical time, critical in decisions such as when and how to point solar panels or satellite imagers.

Still, cautioned McCarthy, "we need to make a decision" about the leap second because engineers are designing satellite systems today that "will be used 20 years from now. We need to do them a service so they're not stuck."

In recent years, time mavens opened a discussion about what to do, and a "general consensus" emerged that "the advantage to astronomy was not worth the pain and suffering of leap seconds," Levine said. "It looked like a done deal."

But it wasn't. Earlier this year Britain's Royal Astronomical Society decried a U.S. proposal to abolish the leap second, suggesting that doing so would disrupt not only astronomers but "all who study environmental phenomena related to the rising and setting of the sun."

Last month, a working group of the International Telecommunication Union meeting in Geneva decided to postpone discussions of the U.S. proposal, which would have abandoned leap seconds in 2007 and let Coordinated Universal Time and astronomical time diverge for several hundred years before inserting a "leap hour."

The working group said more time was needed to form a consensus, and suggested that this year's leap second offered a welcome opportunity to determine whether change is necessary.

"There is a philosophical feeling that abolishing the leap second results in greater decoupling of the time scale from rotation of the Earth, and that this is not a good thing," said McCarthy, a drafter of the U.S. proposal. "But we put up with daylight savings time in the United States, and China has one time zone for the entire country. My own feeling is that we all live with departures."